.gamma.-Butyrolactones are well known solvents and chemical intermediates for complex molecules such as natural products and pharmaceuticals. .gamma.-Butyrolactone, the simplest of these compounds, is a widely used organic solvent, and is produced commercially by several methods. Some .gamma.-butyrolactone is obtained as a by-product in a commercial process for making 1,4-butanediol from allyl alcohol. A potentially attractive route to .gamma.-butyrolactone converts allyl alcohol directly to .gamma.-butyrolactone in a cyclocarbonylation reaction: ##STR1##
Cyclocarbonylation of allyl alcohol to .gamma.-butyrolactone is known. Matsuda et al. (Bull. Chem. Soc. Jpn. 11 (1968) 1876) reported a cobalt carbonyl-catalyzed cyclocarbonylation of allyl alcohol to .gamma.-butyrolactone. The reaction was performed in a CO/H.sub.2 atmosphere at high pressure (about 130 atmospheres). High selectivity to .gamma.-butyrolactone resulted when a nitrile solvent and a pyridine promoter were used. Rhodium carbonyl catalysts were not investigated.
Kaneda et al. (Chem. Lett. (1983) 1465) reacted allyl alcohol with CO under water-gas shift conditions in the presence of a rhodium carbonyl catalyst and a pyridine promoter, and obtained .gamma.-butyrolactone in 68% yield. The process also gave a 21% yield of another C4 product, 1,4-butanediol. Results from a nonaqueous process were not reported.
Sweeney et al. (U.S. Pat. No. 3,061,614) teach a process for making .gamma.-butyrolactone by carbonylating allyl alcohol in the presence of a cobalt carbonyl catalyst. Water or a C.sub.1 -C.sub.4 alcohol is included in the process as a hydrogen donor, and high pressures (&gt;130 atmospheres) are used. Rhodium catalysts and pyridine promoters are not taught.
Alper et al. (U.S. Pat. No. 4,364,780) teach a process for producing lactones from unsaturated alcohols by cyclocarbonylation in the presence of a protic acid and a bimetallic transition metal catalyst. Pyridine promoters and cyclocarbonylation under neutral conditions are not taught.
An improved process for making .gamma.-butyrolactones from allylic alcohols is needed. A preferred process could be performed at relatively low gas pressures under neutral, non-aqueous conditions. A preferred process would give .gamma.-butyrolactone from allyl alcohol as the only C4 product.